Amsoil SS vs Z-ROD

twX said:
I realize that the test at -30 C is extreme for this oil, but I chose to discuss it since it's the only one of the four tests that the authors provided a cranking time for. It's unclear when the engine actually fired up during the -20 and -25 C tests, which makes them more difficult to interpret.



There's a table showing the CCS measurements, but I'm not sure what difference the older test methods would have on these figures. The top two rows are 15W oils. The thickest 10W oils seem to be just above the limits for a modern 10W. The oil used in the Figure 4 test is referred to as a "typical" 10W-40, so I assumed it may be the one that's 4,000 cP at -25 C, but it's unclear. MRV was not provided, but the test oil was said to a "borderline pumping temperature of -29 C, which leads me to believe that it wasn't especially thick compared to a modern 10W.

View attachment 184141

There's some more detailed data on one of the cranking tests with a 10W at -25 C that shows the pre-filter oil pressure rising quickly, indicating that the oil is pumpable. It does take just over 10 seconds, but the engine speed was slowly ramped up to normal cranking speed over the first 10 seconds.

cold-oil-cranking-block-heater-png.184142
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My takeaway from the borderline statement is that it wasn't pumpable at -30C (only down to -29C), which explains the considerable gap between -25C and -30C in your original chart.

Yes, I'd love to see a newer version of this test with a more modern engine and oiling system, as I'm sure you would as well.
 
DuckRyder said:
So a Comp 268H - thats very old lobe profile and i would not consider it an aggressive cam... assuming it is broken in i wouldn't sweat it heavily.
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OVERKILL said:
Perfect, thanks. Yes, I agree with @DuckRyder, that's a pretty mild stick, I wouldn't be concerned with that once broken in.
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Thank you, haven't had time to address all the other questions, lol. But yes it's quite broken in....
Truck Cam Spec Sheet 2.jpg
Truck Cam Spec Sheet 1.jpg
 
OVERKILL said:
Perfect, thanks. Yes, I agree with @DuckRyder, that's a pretty mild stick, I wouldn't be concerned with that once broken in.
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kschachn said:
On the other hand you have a high and persistent MOFT which mitigates the need for replenishment, unless you rev the engine excessively high. On a reasonable start “cold start wear” is not the issue that it is often imagined to be.
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So overall, the robust AW package in Z-ROD would compensate for taking a little longer to "get going" on cold start?
 
DuckRyder said:
So a Comp 268H - thats very old lobe profile and i would not consider it an aggressive cam... assuming it is broken in i wouldn't sweat it heavily.
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Not sweating it, lol, but would there be any benefit at all to using the high ZDDP oil?
 
OVERKILL said:
No, I'm explaining a necessary caveat that needs to be understood when talking about "flow" at start-up.
I didn't say that. Re-read the statement. You won't engage the relief unless the system pressure hits what's required, and that won't happen until the engine is full enveloped, if it happens at all.
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As previously noted by twX, the relief may reach pressure before the cam bearings get oil, that was my point. The relief "sees" pressure before the entire engine is enveloped under extreme examples.


OVERKILL said:
You are missing it.

The pump will only be thrashing the oil by sending it back through the relief, if the system pressure is high enough to do so. This happens only after the engine is fully enveloped, if it happens at all. That's why I provided an "extreme case" example, which you don't appear to have properly processed.
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I was also referring to extreme examples & how it would take longer for a very thick oil at a very low temp to reach the extremities, while "fooling" the relief that the engine is fully enveloped. Can the theory be correlated to less extreme situations? Maybe milliseconds instead of 10-30 sec to reach extremities, but still time, nonetheless?
 
garageman402 said:
I was also referring to extreme examples & how it would take longer for a very thick oil at a very low temp to reach the extremities, while "fooling" the relief that the engine is fully enveloped. Can the theory be correlated to less extreme situations? Maybe milliseconds instead of 10-30 sec to reach extremities, but still time, nonetheless?
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But not particularly relevant because the film thickness is high and persistent due to the high viscosity. There is time.
 
garageman402 said:
I think that it would in some places, such as bearings where a good amount of oil is trapped, but places that get squirt or splash maybe not so much. Under the piston is very hot, & when shut off the extremely hot, thin oil runs away, how long until that area (rings, wrist pins) gets lube on a cold start? How much moly or zinc or phosphorous is left to protect it until fresh lube arrives? Would a 10w-30 hold up better in the under piston area than a 0w-30 or even a 5w-30?

One thing I have noticed using the 0w-30 is after prolonged parking (1-2 months), even after 10 seconds of "flood clear" cranking, the lifters are noisy. In fact one engine barely ran because the lifters weren't pumped up yet. Took about 20-30 seconds for it to start running smooth. That is making me re-think the 0w theory of quick cold flow.
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problem might be the engine, and not the oil. it happens.
 
garageman402 said:
As previously noted by twX, the relief may reach pressure before the cam bearings get oil, that was my point. The relief "sees" pressure before the entire engine is enveloped under extreme examples.
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The relief doesn't "reach" a pressure though, it's experiencing the back pressure from the stack of resistance provided by the engine. While it's possible the stack creates sufficient pressure to engage the relief before the most remote point in the oil system receives volume, it's highly unlikely and these are extreme events that in no way apply to your situation.

It would be like me fretting and freaking out about a Tsunami, which I can't experience in Ontario, or whether my .338LM is capable of dispatching a blue whale if I were to be attacked by one, also, not a possibility.
garageman402 said:
I was also referring to extreme examples & how it would take longer for a very thick oil at a very low temp to reach the extremities, while "fooling" the relief that the engine is fully enveloped. Can the theory be correlated to less extreme situations? Maybe milliseconds instead of 10-30 sec to reach extremities, but still time, nonetheless?
Click to expand...
Again, the questions are:
- What is the relief pressure on your pump?
- Do you hit this pressure when you start the engine?

That needs to be established before we explore this detour any further.

Here's a cold start of my SRT:
Cold start oil pressure - the flow discussion | Bob Is The Oil Guy
 
OVERKILL said:
The relief doesn't "reach" a pressure though, it's experiencing the back pressure from the stack of resistance provided by the engine. While it's possible the stack creates sufficient pressure to engage the relief before the most remote point in the oil system receives volume, it's highly unlikely and these are extreme events that in no way apply to your situation.

It would be like me fretting and freaking out about a Tsunami, which I can't experience in Ontario, or whether my .338LM is capable of dispatching a blue whale if I were to be attacked by one, also, not a possibility.

Again, the questions are:
- What is the relief pressure on your pump?
- Do you hit this pressure when you start the engine?

That needs to be established before we explore this detour any further.

Here's a cold start of my SRT:
Cold start oil pressure - the flow discussion | Bob Is The Oil Guy
Click to expand...
Yes, so it would experience back pressure sooner with 10w oil than with 0w oil. Maybe milliseconds. All other things being equal (which they are not e.g. HTHS, NOACK, etc) 0w would be preferable to 10w in any climate. I get your reference over fretting over something that will not happen. In my climate(s) I'll never see much less than 30F, probably never see 20F. But even in warmer temps is there zero benefit of 0w over 10w? Or do the negative properties of 0w pose a higher risk that outweighs any benefit? I think I know the answer, but I'll still pose the question.
 
garageman402 said:
Yes, so it would experience back pressure sooner with 10w oil than with 0w oil. Maybe milliseconds. All other things being equal (which they are not e.g. HTHS, NOACK, etc) 0w would be preferable to 10w in any climate. I get your reference over fretting over something that will not happen. In my climate(s) I'll never see much less than 30F, probably never see 20F. But even in warmer temps is there zero benefit of 0w over 10w? Or do the negative properties of 0w pose a higher risk that outweighs any benefit? I think I know the answer, but I'll still pose the question.
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What “negative properties”? There are many European approval oils with high HT/HS and a 0W winter rating. What possible negative properties are there? I don’t understand.
 
kschachn said:
What “negative properties”? There are many European approval oils with high HT/HS and a 0W winter rating. What possible negative properties are there? I don’t understand.
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Amsoil SS 0w-30 with the high 8.8 NOACK, and 3.07 HTHS, as opposed to Z-ROD 10w-30 with 5.5 NOACK and 3.6 HTHS
 
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